The present invention relates to a system for quickly changing clamping jaws on a machine tool, usable more particularly for repetitive machining operations.
Up to now, the jaws are mounted on the jaw holder by slow action fixing means, such as screws, bolts and similar devices. Removal of the jaws for removing the machined piece and replacement thereof by the piece to be machined is consequently a slow and expensive operation. In addition, the accuracy of clamping is often insufficient.
The present invention overcomes these drawbacks.
According to the invention, the system for quickly changing clamping jaws on a machine tool is characterized in that it includes locking means for self locking the jaws on the jaw holder, said means being essentially formed of a locking element having a base on one face of which said jaw rests in the locked position, and a bearing part for the jaws, the bearing face of said bearing part being inclined at an angle (.alpha.) with a horizontal plane perpendicular to the plane vertical to said face of said base for cooperating in the locking position, with a corresponding bearing face of the jaw, on the one hand, and on the other, by at least one assembly for holding said jaw in the locking position, one of the ends of a mobile member of said assembly having at least one face inclined through an angle (.beta.) with a horizontal plane perpendicular to the plane vertical to said face of said base for cooperating, in the locking position, with a corresponding bearing face of the jaw, said angles (.alpha.) and (.beta.) being open in the same direction, said angle (.alpha.) being larger than said angle (.beta.); said assembly further including means for unblocking and unlocking said jaw.
Said angle (.alpha.) is from 1.5 to two times the angle (.beta.) and the difference between the angles EQU (.alpha.)-(.beta.)=7.degree. to 10.degree.. EQU [.alpha.=(1.4.div.2).beta.; .alpha.-.beta.=7.degree..div.10.degree.].
The size of the angle (.alpha.) is from 15.degree. to 30.degree., and that of angle (.beta.) from 7.degree. to 20.degree..
Said means of said assembly for unblocking and unlocking said jaws include a pusher, one end of which having at least one inclined face may be in the form of a head or an end piece, and the other end of which allows an adjustable resilient means to be housed, against which said pusher may be pushed back into a bore formed directly or indirectly in said base of said element of the jaw holder, during the operation for unblocking and unlocking said jaw until the face of said end is the same level below the upper face of said base.
A bore is provided in the jaw giving access to the end situated on the jaw side of said pusher for the locking and unlocking operation.
Means for driving the jaw are provided.
These drive means are in the form of grooves disposed on each side of the jaw, or in the form of central keying between the jaw and the jaw holder;
Said drive means are in the form of a pusher which alone ensures the drive for the jaw, when the drive torque is low.
The jaw comprises a heel, which, during blocking and locking of the jaw on the jaw holder, is housed in a corresponding recess in the base of the element of the jaw holder.